Sensitivity to high voltages

[GBDamo]

The electronics within our machines are manufactured to be tolerant of 220V +/-10%. many components have a max 250V allowance.

Now we all know that although our domestic supplies are supposed to be 230V they can vary widely, I personally have measured 257V on one supply.

What in your opinion is the most cost effective way of limiting the supply voltage without causing the to trip due to high voltage conditions.

This is to protect a single device (~3-5 Kw) not the entire installation.

Any useful ideas appreciated.

 

[Pete999]

Do you recommend any particular products??

I could if it was 10 years earlier, but years go on and technology changes, maybe if you looked up UPs and VS companies, explain the scenario and conditions they will be able to advise you. That's what I did and got some good kit, it was used overseas in countries where the supplies weren't reliable, and had no trouble, the VS firm could also diagnose over the phone or by email, the UPs was EMERSON but that's all I remember, hope my reply has been useful, one thing the VS kit was dead simple to connect, loan and supply.

One thing I did find with the UPs, if you are using any form of remote controls or sensing equipment, use a screened cable or twisted pairs to try and avoid voltage pick up, I had one install where the UPs was in a small room which needed to be Air Conditioned, ( it was in Asia so very hot) the customer required an emergency stop for the UPs, which involved a control pair, every time the AC started up out would go the UPs, took me a while to suss out that the control pair was picking up volts from the AC starting and tripped the UPs, worth noting, I think my detective work caused the supplier to add the proviso in their install manual. Clever git aint I?

 

[Lucien Nunes]

Stepping the voltage down with a bucking transformer is a simple and cheap solution if the maximum incoming voltage is high but the percentage variation is no more than the board's total tolerance. I.e., you don't need to stabilise, merely adjust your range of incoming voltages to align with the range the board will accept.

Suppose you find your supply only ever varies from 230-260V, while the board wants to see 207-253. You could reduce your midpoint 245V down to their midpoint 230V, making the max voltage 260-15=245V which is 8V within spec for the board, and your min 230-15=215V which is equally in spec. For a 3kVA device your bucking transformer has to knock 15V off the supply while handling 3000/215=14A, so a transformer of 15*14=210VA would do the job. In practice you would want to allow a bit more margin but you can get this for under £30 e.g. | 2 Output Toroidal Transformer, 225VA, 2 x 15V ac | - http://uk.rs-online.com/web/p/toroidal-transformers/6719034/

Primary across the mains, secondaries in parallel, in antiphase series with the load. Note that with a toroidal the secondaries may not be insulated from the exterior for the primary voltage - you might need to use extra insulating washers, or choose an EI-frame transformer instead. A regular autotransformer is ideal, especially if it has suitable taps to give you a bit of leeway, but the bucking method is usually by far the cheapest.

Note also that the board's method of measuring the voltage may not be the same as your true-RMS meter. It might have a basic method of measurement that is misreading high due to waveform distortion, even though your meter is giving a correct measurement.

 

[GBDamo]

Thanks for that. Will look into it and try to get my head round it all. Expect me back asking what it all means.

 

[Marvo]

Before throw large amounts of money at the problem I'd spend some time and effort establishing if there actually is one. I'd put a PQA on the supply and gather a few days or preferrable a week of data to establish the power quality and pinpoint precisely the issues.

Pointing a finger at power quality is a 'get out' that's often tried by suppliers to limit their warranty exposure when they're selling products that have high failure rates due to poor design or build quality. Having solid evidence will put the ball back in their court.

 

[marconi]

These domestic voltage regulators reduce voltage to 220V. You would need to check their specification to see if they can maintain this regulation for the power you intend to draw through it.

Energy Ace Voltage Optimizer | Single Phase | ExpertElectrical.co.uk - https://www.expertelectrical.co.uk/circuit-protection/energy-ace-voltage-optimizer?fee=3&fep=18383&gclid=EAIaIQobChMI7ffOx5rU1wIV7pPtCh26bg6hEAQYBSABEgIQ-vD_BwE

Eco-Max Home Voltage Optimisation 63 Amps - https://www.savemoneycutcarbon.com/product/eco-max-home-voltage-optimisation-63-amps/?gclid=EAIaIQobChMI7ffOx5rU1wIV7pPtCh26bg6hEAQYASABEgLkmfD_BwE

This one below regulates at preset 220V for power consumption up to 2.5kW permanently and up to 4.5kW for about 10-20 minutes and then switches to bypass to output the prevailing mains voltage:

VPhase Voltage Optimiser | REUK.co.uk - http://www.reuk.co.uk/wordpress/energy-efficiency/vphase-voltage-optimiser/

 

[freddo]

I thought Vphase went bust. I would not recommend such a product though. Something by Stac would be much more robust and reliable, using transformer technology rather than masses of electronics. I have one of their little models, it works well. Not that I have a use for it.

The mention of 220V suggests the product is Chinese crap. I'd recommend throwing the machine away.

 

[mydigitalhome]

Hi I work a lot outside of UK with high voltages above 250v and tried expensive voltage optimisation units coving complete systems to UPS covering light circuits and sensitive equipment only. Lighting drivers and automation systems often become temperamental at >247v with nuisance faults so always mindful of voltage when pricing jobs.